1. Field of the Invention
The present invention relates to a driving module, driving method, and liquid crystal display (LCD) device, and more particularly, to driving module, driving method, and liquid crystal display (LCD) device capable of achieving a dot inversion driving effect without changing the conventional structure and line inversion operations via shifting source voltages and a common voltage by half a horizontal synchronization signal cycle.
2. Description of the Prior Art
An LCD device utilizes a source driver and a gate driver to drive pixels on a panel to display images. Since the cost of a source driver is higher than that of a gate driver and the amount of circuitry of source driver is greater than that of a gate driver (under the situation of 480×272 pixels, since each pixel includes a red subpixel, a green subpixel, and a blue subpixel, circuitry of the source driver corresponding to 1440 data lines and circuitry of the gate driver corresponding to 272 scan lines are required), a dual gate structure is thus developed in order to reduce the amount of source drivers. In short, for the same amount of pixels, the dual gate structure has half as many data lines, and twice as many scan lines, in order to reduce the cost.
In order to avoid repeatedly driving liquid crystal molecules with voltages having the same polarity (positive or negative), thereby reducing polarization or refraction properties of the liquid crystal molecules that will deteriorate image quality, the liquid crystal molecules need to be alternately driven by positive and negative voltages, e.g. line inversion. In other words, an LCD device includes a glass substrate with a common voltage and another glass substrate with a driving circuit and liquid crystal molecules in between, and thus when the LCD device is driven in line inversion by an alternating common voltage (between −5V and 5V for low voltage driving), the alternating common voltage and a source voltage are applied to subpixels to generate a voltage difference, i.e. the source voltage minus the common voltage, to alternately drive the liquid crystal molecules with positive and negative voltage.
Please refer to FIG. 1, which is a schematic diagram of an LCD device 10 with a dual-gate structure according to the prior art. For clear illustration, the LCD device 10 only includes a source driver 100, a gate driver 102, a timing controller 104, data lines S1-Sm, scan lines G1-Gn and a pixel matrix Mat. The timing controller 104 utilizes a horizontal synchronization signal Hsync and an output enable signal Ena to control the source driver 100 and the gate driver 102, respectively, to generate data driving signals Sig_S1-Sig_Sm and gate driving signals Sig_G1-Sig_Gn, so as to charge the pixel matrix Mat. In the pixel matrix Mat, which is a dual-gate structure, each pixel includes a red subpixel RS, a green subpixel GS and a blue subpixel BS, and each subpixel includes a transistor and a capacitor, which are denoted by blocks for simplicity. In the view of columns, subpixels of every two subpixel columns are controlled by a same data line. For example, the red subpixel column RS1˜RSn and the green subpixel column GS1˜GSn are controlled by the data line S1, the blue subpixel column BS1˜BSn and the red subpixel column RS1′˜RSn′ are controlled by the data line S2, and the green subpixel column GS1′˜GSn′ and the blue subpixel column BS1′˜BSn′ are controlled by the data line S3, and so on. In the view of rows, subpixels of each row are controlled by two adjacent scan lines. For example, in a row Row_1, the red pixel RS1, the blue pixel BS1 and the green pixel GS1′ are controlled by the scan line G1, and the green pixel GS1, the red pixel RS1′ and the blue pixel BS1′ are controlled by the scan line G2. Other rows Row_2, Row_3 . . . Row_n are arranged in the same way.
Please refer to FIG. 2A to FIG. 2C. FIG. 2A is a schematic diagram of driving the pixel matrix Mat of FIG. 1 in line inversion with an alternating common voltage, and FIG. 2B and FIG. 2C are schematic diagrams of polarities of subpixels of the pixel matrix Mat of FIG. 2A in frames Fn, Fn+1, respectively. The following description utilizes FIG. 2A to illustrate operations of the red subpixel column RS1˜RSn and the green subpixel column GS1˜GSn corresponding to the data line S1. In detail, in a horizontal synchronization signal cycle Line2, the scan lines G1, G2 are sequentially turned on in periods Tgo, Tge, respectively, such that a source voltage Vs corresponding to the data driving signal Sig_S1 can be applied to the subpixels RS1, GS1 corresponding to the scan lines G1, G2 in periods Tso, Tse, respectively, wherein the periods Tso, Tse are half the horizontal synchronization signal cycle Line2. Since level changes of the source voltage Vs and a common voltage Vcom are synchronized with the horizontal synchronization signal Hsync, polarities of a voltage difference of the source voltage Vs minus the common voltage Vcom for charging the subpixels RS1, GS1 are positive in a frame Fn, and negative in a frame Fn+1. Similarly, in a horizontal synchronization signal cycle Line3, the subpixels RS2, GS2 corresponding to the scan lines G3, G4 are charged with negative polarities in the frame Fn, and are charged with positive polarities in the frame Fn+1. By the same token, polarities of other subpixels of the red subpixel column RS1˜RSn and the green subpixel column GS1˜GSn and polarities of subpixels of subpixel columns corresponding to other data lines can be derived. In such a situation, as shown in FIG. 2B and FIG. 2C, polarities of subpixels in a same row and alternating rows are the same, e.g. the row Row_1 and the row Row_3, the row Row_2 and the row Row_4, and so on, which achieves the effect of line inversion.
However, when driving the dual-gate structure in line inversion, the polarities of subpixels in the alternating rows are the same, which causes lateral crosstalk between subpixels. For example, when an image is meant to show black in the center area and grey in other areas, the left and right parts relative to the center area are lighter due to the lateral crosstalk between subpixels. Thus, there is a need for improvement.